The present invention relates to a force sensor, in particular a pressure sensor, having a diaphragm-like carrier made of ceramic, on which are arranged thick-film resistors and a circuit of strain-sensitive thick-film conductor tracks, which are formed as a Wheatstone bridge connecting the thick-film resistors to one another.
In known force sensors, the thick-film resistors and the thick-film conductor tracks are printed onto a carrier made of ceramic by screen printing and subsequently sintered thereon by a sintering process. Afterward, discrete components such as capacitors, ICs or transistors can be soldered onto the thick-film conductor tracks or be contact-connected by silver conductive adhesives.
For the measurement of pressures, resistive pressure sensors are increasingly being used inter alia in applications in the automotive sector. The strain-sensitive thick-film resistors, connected up to one another as a Wheatstone bridge, alter the offset signal present under mechanical bending of the diaphragm-like carrier. What is responsible for this is the so-called k-factor or gauge factor of said thick-film resistors which is a material-specific gain factor.
If low pressures are intended to be measured by the force sensor, only small output signals of a few millivolts are obtainable. These small signals are processed poorly by an electronic unit connected downstream compared to larger signals.